The present invention relates to a lens unit; a light emitting diode (LED) head including the lens unit; an exposure device including the lens unit; an image forming apparatus including the exposure device; and a reading apparatus including the lens unit.
A conventional lens unit is used as an optical system capable of forming an erected same-size image of an object in a line, and is arranged arrangement in an image forming apparatus of an electro-photography type or a reading apparatus such as a scanner and a facsimile. The image forming apparatus uses an LED (Light Emitting Diode) head in which a plurality of LEDs is arranged in a linear arrangement. In the reading apparatus, an image of an original is formed on a light receiving unit formed of a plurality of light receiving elements arranged linearly.
The conventional lens unit as an optical system includes a lens pair formed of a lens for forming an inverted reduced-size image of an object and a lens for forming an inverted enlarged-size image of an object. A plurality of the lens pairs is arranged substantially linearly, so that the erected same-size image of an object is formed in a linear arrangement. (refer to Patent Reference).
Patent Reference: Japanese Patent Publication No. 2008-87185
In the conventional lens unit, a plurality of the lens pairs is arranged substantially linearly. Accordingly, when light leaking from one of two lenses arranged next to with each other is incident on the other of the two lenses, the image forming apparatus forms an image with low contrast, thereby deteriorating a resolution of a projected image formed with the lens unit.
In view of the problems described above, an object of the present invention is to provide a lens unit capable of solving the problems of the conventional lens unit and forming an image with a high resolution.
Further objects and advantages of the invention will be apparent from the following description of the invention.